Coatings of metal have been applied to a variety of substrates for many years. Such coatings are often used to provide corrosion resistance, and recently to achieve magnetic effects. A particularly effective corrosion resistant coating includes zinc. Automobile exterior body parts, namely, fenders, door panels, and the like are among the most difficult parts to protect from corrosion because of the environment to which they are exposed and their susceptibility to surface damage tending to create corrosion sites.
Currently, automobiles and trucks are protected from corrosion by a zinc or zinc alloy layer coated on the steel before vehicle fabrication. Since the zinc rich metal coating protects steel sacrificially at damage sites in the paint, the corrosion resistance in the vehicle is increased dramatically. There is, however, a drawback in that the metallic zinc or zinc alloy must be applied to the steel prior to manufacturing of the vehicle. Hence, operations such as blanking, welding, and painting occur after a zinc coating has been applied to the steel. Welding tip life is significantly reduced in the presence of zinc coatings and various forming operations are hindered by zinc accumulating in dies. A zinc-based coating is not applied after vehicle assembly because there is no suitable method to apply it. For example, electro-deposition of a zinc coating onto completed, assembled parts does not provide coverage to convoluted parts and recesses in parts. Electro-deposition is simply not able to provide a uniform metal coating on complex shapes and in cavities. It would be desirable to obtain a protective corrosion resistant coating which is easy to apply to surfaces of objects regardless of their configuration, which provides an essentially uniform coating on the surfaces, which may be applied after assembly of componentry, and which is compatible with subsequent operations such as painting.